Automatic control of refrigerating apparatus



Nov. 15', 1938.- 5. OTTO ET AL 2,137,060

' AUTOMATIC CONTROL OF REFRIGERATING APPARATUS Filed Oct. 5,-1934 2Sheets-Sheet l BY m 42W rww I ATTORNEYS Nov. 15, 1938. s. OTTO ET AL2,137,060

AUTOMATIC CONTROL OF REFRIGERATING APPARATUS r: .2 7a 7 a I 7 A I w 796f 6 HEAT'NG PERIOD Filed 001;. 5, 1934 2 Sheets-Sheet 2 FIRST PART OFABSORFTION PERIOD MIDDLE PART OF ABSORPTION ,PERIOD END PART OFABSORPTION PERIOD 56 ww yfw B$awmwl2whl 4ZM7M/M ATTORNEY 5 I sorptionmay set in as quickly as Patented Nov. 15, 1938 UNITED STATES PATEN T,OFFICE AUTOMATIC CONTROL or nnmmnm'rmo APPARATUS Stuart Otto, New York,and Lawrence Bruehl, Brooklyn, N. Y., assignors to Gas RefrigerationCorporation, Scranton, Pa, a corporation of Delaware Application0ctober'5, 1934, Serial No. 746,940

,. Y 110mm,.

ammonia or other refrigerating gas from the absorbent, and deliver itunder pressure to a-condenser where it is liifuefled, and during. thecoolmg period, operates as. an absorber to cause a reduction in pressureby the reabsorption of the gas, at reduced pressure and an evaporationof the liquefied gas in the evaporator. The lengths of the successiveheating and cooling periods may i be controlled ,in accordance with thetemperature of the evaporator, and/or in accordance with thetemperature'in the boiler absorber, or in various other ways.

, One object of the present invention is to provide new and improvedmeans for preventing the heat of the burner or heating element frombeing radiated or conducted to the storage chamber of the refrigeratorduring the heating period.

Another object is to provide new and improved means for dissipating theheat from the .boiler absorber as promptly as possible after the burneror heating element is turned off, so that abpossible after the end ofthe heating period.

Another object is to provide an automatic control of the cooling aircirculation, which permits the-use of a minimum sized condenser, and, ifa liquid cooling medium is used for condenser cooling, to permit the useof a minimum sized tank for said medium.

One way in which we may carry out the invention is to provide a casingsubstantially enclosing the boiler absorber and the burner, and forminga passageway around said boiler absorber for the circulation of air. Asa feature of the present invention, the circulation of air through thispassageway is controlled by an automatically oper-' able valve which isclosed during the heating period to prevent undue circulation of air inthis passageway except that necessary to maintain combustion from theburner in case combustible gas is used as the heating medium, and whichis opened in accordance with certain predetermined conditions, such asthe temperature near the boiler absorber to increase the circulation ofair through said passageway either by natural air or by forced draft.

As another feature of the invention, we provide another casingsubstantially encircling and spaced from the first casing to form asecond or outer passageway, the circulation of air through said secondpassageway being controlled by an automatically operable valve which isopened during the heating period, so that the heat radiated or conductedoutwardly from the inner passageway will be carried awayby thecirculation of air through said outer passageway, and

Y is thereby kept away from the storage chamber of the refrigerator.'I'hisvalve is closed at the end of the heating period so that the majorportion of the forced or induced air is permitted to go through theinner passageway and around the boiler absorber to dissipate the heatfrom said boiler absorber.

As another feature of the present invention, we provide a fan which isadapted to assist in the circulation of air .around the boiler absorber,and which is automatically controlled in accordance 'with predeterminedphases of the refrigerating cycle.

Various other features and advantages of the invention will be apparentfrom the following particular description, and from an inspection oftheaccompanying drawings in which:

Fig. 1 is a diagrammatic side view, partly in section, of a refrigeratorhaving our improved automatically controlled cooling air circulatorysystem,

Figs. 2 and 3 are vertical sections showing different forms ofautomatically controlled cooling air systems, Fig. 4 is a somewhatdiagrammatic view of a system for controlling the operation of a fanand/ phases in the refrigerating cycle.

Fig. 5 is a diagrammatic view showing different provided a boilerabsorber l0 including an upper chamber or vessel I I, and a lower vesselH. The boiler absorber I0 is shown attached to the rear of arefrigerator storage chamber I3 containing an evaporator Ill. ,PAbovethe boiler absorber III and alongside of the storage chamber I3 is acondenser Hi; In case the condenser is water cooled, the water tanktherefor may be positioned in the position indicated for the condenser.

For heating the boiler absorber Hi there is provided one or more burnertubes l6 disposed directly under the vessel l2 in position to direct theheat therefrom onto said vessel.

The refrigerating system shown is of the usual intermittently operatedabsorption type in which, during the heating period, the refrigerating.medium, such as ammonia, is boiled off from the boiler absorber l0, anddelivered to the condenser l5 where it is liquefied and then to theevaporator. When the heating period terminates the boiler absorber iscooled and the liquefied refrigerating medium is evaporated in theevaporator l4, and returned to the boiler absorber Ill where it isreabsorbed.

The connections between the boiler absorber, the evaporator and thecondenser, may be the usual ones and have not been illustrated as weclaim no novelty in that part of the system.

The boiler absorber I is substantially enclosed in a casing II which isspaced from the boiler absorber ID to form an air circulatory passagewayaround said boiler absorber, and which has the sides thereofsubstantially following the contour of the sides of the two vessels Hand I2, so that the hot gaseous products of combustion from the burnersl6 will be kept very close to the walls of the boiler absorber. Thecasing I1 is connected at the top with a flue l9 extending upwardly toan outlet at the top of the refrigerator.

The lower end of the casing I'I extends to a position near to or belowthe burners l6, and is provided with an opening 20 formed between a sidewall 2| and a bottom wall 22 of said casing.

ubstantially enclosing the casing I1 is an o ter casing 23 spaced fromthe walls of the inner casing I1 and forming therewith a second aircirculatory passageway 24 around said casing il. As shown, the outerrear wall 25 of this outer casing 23 may constitute the rear wall of therefrigerator.

The outer casing 23 has a flue 26 encircling the flue [9 but spacedtherefrom, and extending to an outlet at the top of the refrigerator.The inner front wall 21 of the outer casing 23 is spaced from the facingwall of the storage chamber l3 so as to form an air passageway 28between said chamber and said outer casing 23.

The flues l9 and 26 are disposed towards the rear sides of the casingsI! and 23, and the condenser l is disposed between said flues and therear of the storage chamber l3 to form a passageway 29 around saidcondenser.

As an important featureofthe present invention, the passage of airthrough the opening 20 of the inner casing I1 is controlled by a valvein the form of a damper 30 which is automatically operable so as toclose the opening 20 during the heating period so that substantially allof the heat from the burners I6 is retained in the inner casing l1, andwhich is moved in open position at the end of the heating period toincrease the circulation of air into the inner casing l1 and around theboiler absorber ID to cool said boiler absorber so that absorption mayset,in as quickly as possible after the: end of the heating period.

In the form shown in Fig. 1, the damper 30 is thermostaticallycontrolled and for that purpose is connected .to the bottom wall 22 ofthe inner casing H by a thermostatic bimetallic strip 32 so that theunequal expansion" or contraction between the component metals of thestrip causes said strip to curve in accordance with the localtemperature-conditions. This bimetallic strip is so constructed thatduring the heating period when the burners iii are on, the damper 30 isin closed position as shown. As soon as the burners l6 are shut off thelowering of the temperature aroundthe bimetallic strip 32 causes thedamper 30 to be moved into open position indicated in dotted lines. Theinner casing I1 is provided with apertures 3! to permit the passage ofsufficient air into said casing to support combustion from the burnersit during the heating period if combustible gas is used as the heatingmedium.

As another feature of the present invention, the circulation of airthrough the passageway 24 between the two casings l1 and 23 and throughi the passageways 28 and 29, is controlled by means of the damper 30 andan automatically operable valve in the form of a damper 33. This damper33 in the form shown in Fig. 1, is thermostatically operated and forthat purpose is fixed to the side wall- 2| of the inner casing I! bymeans of a thermostatic bimetallic strip 34. The damper 33 isadvantageously curved to conform with the side portion of the innercasing .il opposite thereto, so that in open position shown, said damperwill be close to said side portion to permit the free passage of airthrough the two passageways 28 and 29. In closed position indicated indotted lines, the upper portion of the damper 33 will extend through aslot 35 in the outer casing 23 and transversely through the passageway28, so that the circulation of air through said passageway 28 and thefront side of the passageway 24, is blocked. The passage of air throughthe rear side of the passageway 24 is advantageously controlled by thedamper 30 which, when disposed in open position shown in dotted lines,engages a wall 36 extending transversely from the lower end of the rearwall 25 of the outer casing 23, and thereby blocks the passage of airthrough said rear side.

The bimetallic strip 34 is so constructed and arranged that when thedamper 30 is in open position, at the end of the heating period, the

damper 33 is in the position shown in dotted lines to block the passageof air through the passageways 24 and 28. However, when the damper 30 isin closed position, the damper 33 is in position closely adjacent to thewalls of the inner casing I! as shown, so that the passageways 24 and 28are free to permit circulation of air therethr'ough.

In the operation of the form of device shown I -ers l6 may be kept veryclose to the walls of the boiler absorber ID. The heat absorbed by theinner casing walls will be radiated inwardly towards the boiler absorberIn so that the heat is effectively applied to the parts to be heated.Some of the heat from the interior of the inner casing I! will beradiated or conducted outwardly, but it will be carried away by the airwhich enters the passageway 24 between the two casings I1 and 23. Ifnatural draft is utilized, this air current will be induced by theheating action of the inner casing and also by the ejector action of theinner flue l9. Also, during the heating period, there is induced orcreated an air circulation in the passageways 28 and around thecondenser l5, so that radiation from the'outer casing 23 to thecondenser l5 or the storage chamber I3 is minimized during this period.

The cooling of the inner casing. I! by the air current between the twocasings l1 and 23' is such that even when the boiler absorber is at itshighest temperature, there will be very little heat radiated orconducted to the atmosphere of the room from the apparatus. Furthermore,the air drawn through the passageway 24 between the two casings andthrough the passageway 28 mixes with, dilutes and'cools the gases fromthe flue I9, so that there is the minimum heat radiated to the room fromsaid flue.

At the end of the heating period, the burners l6 are turned off. Theconsequent lowering of the temperature adjacent to the bimetallic strips32 and 34 causes the opening of the damper and the closing of the damper33. Under these conditions, air is permitted to circulate freely withinthe inner casing l1, and around the boiler absorber l0, so that saidboiler absorber is quickly cooled and absorption will set in as quicklyas possible. The closing of the passageways'24 and 28 during theabsorption period causes a larger amount of air to be induced or forcedthrough the inner casing l1.

In order to. assist in the circulation of air through the various airpassageways and flues, a fan 39 may be used as shown, secured to thebottom of the refrigerator and adapted to blow air through the variouspassageways and lines.

.The fan may be continuously operated or may be intermittently operatedin accordance with the cycle of operation of the refrigerating system,and in accordance with certain features of the invention, as will bemore fully described hereinat er.- 1

In Fig. 2 is shown another form of damper arrangement for controllingthe circulation oif air through the various passageways and flues. Inthis construction, the invention is shown,as applied to a" boilerabsorber comprising a single vessel or chamber 40. In this construction,the

' vessel 40 and burners l6 are substantially enclosed in an inner casing4| open on its front side, spaced from the walls of said vessel 40 toform an air passageway 42 around said vessel, and having the top wallthereof substantially following the contour of said vessel. This innercasing 4| at the top thereof has a flue 43 which communicates with thepassageway 42.

1 Substantially encircling the inner casing 4| is an outer casing 44spaced from the walls of said inner casing and-forming therewithapassageway 45. 45 and a bottom wall 41, andterminates at its inner sidein a tubular extension 49. At the upper end of the outer casing 44 is aflue 49, en-

circling the flue 43 but spaced therefrom.

'innercasing4l through a bimetallic strip 52, '70

The circulation of air between the passageways and flues in thisconstruction, is controlled by a pair of automatically operable valvesin the form of dampers 50 and 5| cooperating with the open side of theinner casing 4| and thermostatically controlled. Forthat purpose, thedamp-' er 50 is connected to the "bottom wall of the while the damper 5|is bimetallic in its entirety, and is connected to the top wall of saidcasing.

When the burners l6 are, on, the temperature,

adjacent to the thermostatic members 5| and 52 is such as to bring thetwo dampers together into engagement as shown, so that the open side ofthe This outer casing 44 comprises a rear wall inner casing 4| isblocked while the passageway 45 between the two casings 4| and 44 isopen for the passage of air therethrough. When the burner |6 has beenturned oil? the lowering of the temperature causes the dampers 50 and 5|to move apart and into engagement with the walls of the outer casing 44,as shown in dotted lines, to permit the free entry of air into the innercasing 4| and to block the passage of air in the passageway 45 betweenthe inner and outer casings. I

The open side of the inner casing 55 is controlled by the damper 54connected to one end of a pair of brackets 6| by means of bimetallicstrips 62, the other ends of the brackets being connected to the rearwall of said casing. The damper 54 is in the form of a hood having anend wall 63 and a pair of side walls 54 spaced a slightly greaterdistance than the width of the wall extension 51- so that said dampermay swing freely under the action of the thermostatic strips When theburners it are on, the damper 54 will be in the position shown, withthe-end wall 63 thereof extending between the bottom wall 55 and thewall extension 59 of the inner casing, so that the passage of air intothe interior of the inner casing 55 is blocked, while the air ispermitted to enter the space between the two casings 44 and 55. When theburners l6 are shut oil, the damper 54 will -be automatically moved inits uppermost position into contact'with the wall of .the outer casing44 so as to permit air to enter freely into the interior of the innercasing 55- and to block the upper portion of the inlet end of thepassageways between the'inner and outer casings. Although the lowerportion of thepassagewa'y between the inner-and outer casings is,

open in this position of the damper 54, very little air will passthrough this'lower portion of the passageway at this .point, due to thefact that most of the air induced or forced will pass into the interiorof the. casing 55 as a result of its comparatively larger opening.

'- In Figs. 4 and 5 is shown a unit for automatically controlling thedamper and/or the-fan according to-certain phaseslin the refrigeratingcycle. This feature of the invention is shown as applied to anelectrical system in which an electrical burner is but as far ascertainaspects of this feature are concerned, it may be applied to a system in,which combustible gas,

steam, hot oil, or other suitable fluid is used as v the heating medium.In this construction, there is provided-a pair of valves 65 and 65 forcontrol ling the flow of heating medium, such as electric, l

current. the form of mercury switches thermostatically controlled fromthe boiler absorber and evaporator respectively. For that purpose,within the boiler-or associated in heat' exchange relationship thereto,there is employed a temperature bulb 61 for a fluid medium which willexpand These valves 55 and 56 are shown in and contract with changes intemperature in the boiler absorber, and this is connected to the switch65 by a suitable operating mechanism 68. In the evaporator, there isemployed a similar temperature bulb 18 connected to the switch 66 by theoperating mechanism The operating mechanisms 68 and II are of the snaptype, so that the switches 65 and 66 are held in position betweenpredetermined temperature phases in the boiler absorber and theevaporator.

The current comes in through a pair of main lines 12 and 13, the line I2having a branch connection 14 to one side of a heating element or burner15, and abranch connection 16a to one side of the fan 39. The other line13 comes into the middle contact point of the switch 66.

The right-hand contact point of the switch 66 is connected by means of aline 16 to the righthand contact point of the switch 65, while theleft-hand contact point of the switch 66 is connected to the middlecontact point of the switch 65 by means of a line 11. The line H isconnected to the other side of the fan 39 by means of a line 11a. Theleft-hand contact point of the switch 65 has a branch connection." tothe other side of the heating element 15 and another branch connection19 to one side of an electrically operated mechanism 88 for a damper 8|.The other side of this operating mechanism 88 is connected to the branchconnection "a by means of a connection 82.

The operating mechanism 88 may be of any suitable construction. Forinstance, it may comprise a solenoid 83 having a plunger 84, one

end of which is in the form of a rack bar meshing with'a toothed wheel85, the shaft of which carries the damper 8|, so that as the circuitthrough the solenoid 83 is opened or closed the corresponding movementof the plunger 84 causes a movement of the damper 8|.

The switches 65 and 66 are so operated as to cause the operation of thefan 39 during the heatm period and during a portion of the absorptionperiod, and also causes the operation of the damper 8| coincidentallywith the closing and opening of the circuit through the heating element[5.

In Fig. 5 is shown the diiferent positions of the thermostatic switches65 and 66 during the refrigerating cycle. During the heating period, theswitches 65 and 66 are in the position indicated in Fig. 4 and at Ain'Fig. 5. In this position, the heating element 15 is on, the circuitof the fan 39 is closed, and also the circuit of the electricaloperating mechanism 88 so that the damper 8| is closed, and the air isblowing between the inner and outer casings, thereby preventing outwardradiation of heat from the inner casing. During this period, there is acompara tively low temperature in the boiler absorber as the gas ispassing of]? freely to the condenser, and

there is comparatively high temperature in the evaporator as there is noevaporationor cooling efiect taking place.

As the. heating of the boiler absorber continues, the operation willreach a point at which all of the ammonia or other refrigerant gas hasbeen driven ofi, and the temperature will rise to such a point in theboiler absorber that the fluid in thetemperature bulb 61 in expandingwill exert suflicient pressure to cause the reversal of the switch 65 tothe position B shown in Fig. 5, while the thermostatic switch 66 remainsunchanged. In this position of the switches, the circuit through theheating element 15 will be opened so that the heat from said elementwill be shut off. Also, during this phase, the circuit of theelectrically operated mechanism 88 will be opened so that the damper 8|will move into position to permit passage'o'f air into the inner casingand around the boiler absorber unit to cool said unit. The temperatureof the boiler absorber will then drop and evaporation in the evaporatorwill begin.

. During the middle portion of the absorption period, as the evaporatortemperature drops, the pressure of the thermostatic medium in thetemperature bulb 18 will decrease sufficiently to cause the switch 66 toreverse into position C shown in Fig. 5, While the switch 65 remainsunchanged. In this position, the circuit of the fan 39 will still beclosed so that the fan will still be operating while the circuits of theheating elements 15 and the operating mechanism 88 will still be open sothat no change takes place in the operation of these members.

During the latter part of the absorption period, the cooling of theboiler absorber unit will cause the switch 65 to move into the positionD shown in Fig. 5, while the position of the switch 66 the damperoperating mechanism 88, the fan 39,

and the heating element 15 will be closed so that these members will beoperated and the heating period will begin.

The constructions shown in Figs. 4 and 5 may be applied to theconstructions shown in Figs. 1-3 for operating the dampers and the fan.

In Fig. 6 is shown another form of unit for controlling the operation ofthe fan 39. Inthis construction the fan 39 may be operated independentlyof the operation of the heating member flow through a fluidv supply pipe9|, while the other line 81 is connected to the other pole of this fiuidvalve 98. The supply pipe 9| is connected to a heating element 92 shownin the form of a gas burner, and hasa pilot 93 in its line.

Connected across the lines 86 and 81 is the fan 39 and an automatictemperature switch 95 disposed in the boiler absorber unit.

In the operation of this system, during the heating period, bothswitches 88 and 89 are closed so that the circuit of the electricaloperating mechanism of the fluid valve 98 is closed,

and said valve is opened to permit the passage of gas to the burner 92.As soon as the temperature of the boiler absorber unit has reached apredetermined temperature, the switch 88 is opened while the switch 89remains closed, so that 92, thereby starting the boiling period.

The temperature switch 95 can be so regulated as to effect any desiredoperation of the fan 39. For instance, it may be so regulated as tooperate the fan during the boiling period, and during a portion of theabsorption period, or it may be operated only during the absorptionperiod, de-.

pending upon the adjustment of the switch 95.

Having thus described our invention, what we clairin; as new and desireto secure by Letters Pat- 8H2 1. A refrigerating apparatus of theintermittently operating absorption type, including a boiler absorber, acasing extending around said boiler absorber, spaced therefrom to form apassageway therewith, and having .an inlet opening, means for heatingsaid boiler absorber intermittently, a damper extending across saidinlet opening, and thermostatic means directly connected to said damperfor automatically moving the latter into closed position while saidheating means is in operation, and for moving said damper into o iifenposition when said heating means is turned 0 2. A refrigeratingapparatus of the intermittently operating absorption type, including aboiler absorber, a casing extending around said boiler absorber, spacedtherefrom to form a passageway therewith, and having an inlet opening,means for heating said boiler absorber intermittently, a damperextending across said inlet openin, and a bimetallic thermostatic stripconnected between said damper and the wall of said casing for movingsaid damper into closed position while said heating means is inoperation, and for moving said damper into open heating means is-turnedoflf. I

3. A refrigerating apparatus of the intermittently operating absorptiontype, including a boiler absorber, an inner casing extending around saidboiler absorber and spaced therefrom to form position when said apassageway therearound, an outer casing extending around said innercasing and spaced therefrom, means for heating said boiler absorberintermittently, thermostaticallyoperated valve means for controlling thecirculation of air between said casings, and separate thermostaticallyoperated valve fneans for controlling the circulation of air through theinner casing.

4. A refrigerating, apparatus of the intermittently operating absorptiontype, in which the cycle of operation includes a heating period and anabsorption period, including a boiler, an inner casing surro' indingsaid boiler and spaced therefrom, said casing being provided with aninlet opening, an outer casing extending around said inner casing andspaced therefrom to form a passageway therewith, a damper for the inletopening of said inner casing and means thermostatically operable formoving said damper v.altemately in closed and open position at thebeginning and end of the heating period respectively, said damper inopen position engaging the outer cas 'ing wall and blocking the passageof at least a into engagement with the outer casing at the portion ofthe air into the said casings.

5. A refrigerating apparatus of the intermittently operating absorptiontype in which the cycle of operation includes a heating period and anabsorption period, including a boiler absorber, an inner casingsurrounding said boiler absorber and spacedtherefrom, said casing beingprovided with an inlet opening, an outer casing extending around saidinner casing, spaced therefrom, and also having an inlet opening, a pairof dampers connected to the wall of said inner casing, and means forautomatically controlling said dampers whereby the latter, during theheating period, will be together to block the passage of air into theinner casing, and will be moved apart and passageway between end of theheating period to permit free passage of air into said inner casingwhile blocking the passage of air between said casings.

6. A refrigerating apparatus of the intermit- "tently'operatingabsorption type in which the cycle of operation includes a heatingperiod and an absorption period, including a. boiler absorber,

a casing around said boiler absorber, a condenser outside'of saidcasing, a fan, means for automatically controlling the operation of saidfan, whereby said fan is operated during the heating period and shut offbefore the end of the absorption period, and automatically operablemeans for directing the air from said fan only over said condenser tocool the latter during the heating period, and only through said casingduring the absorption period to cool said boiler absorber.

7. A refrigerating apparatus of the intermittently operating absorptiontype, in which the cycle of operation includes a heating period and anabsorption period, including a boiler absorber, an evaporator, a heatingelement for said boiler absorber, a fan, a valve for-controlling thecirculation of cooling air from said fan and around said boilerabsorber, means for operating said valve and Tsaid heating elementcoincidpntly and intermittently in accordance with temperatureconditions in said boiler absorber, and means an absorption period,including a boiler absorber,

an evaporator, an electric heating element for said boiler absorber, afan for circulating cooling air, an electrically operated member forcon-' trolling the circulation of air around said boiler absorber, and apair of switches for controlling the passage of electric current to saidheating element, to said member, and to said fan, and

automatically operable respectively by the temperature in the boilerabsorber and the evaporator, whereby said electrically operated valve isoperatd at the beginning and end of the heatlng period, and said fan isoperated during'said boiling period and during a portion of said ,ab-

sorption period, and is turned off before the end of said absorptionperiod.

9. A refrigerating apparatus of the intermittently operating absorptiontype, including an absorber, a casing around said absorber, and meansfor circulating cooling air around substantially the entireouterperiphery of said casing 11. A refrigerating apparatus of theintermittently operating absorption type, including a boiler absorber,an inner casing extending around "said boiler absorber and spacedtherefrom to form a passageway therearound, an outer casing extendingaround said inner casing and spaced therefrom to form a passageway, andmeans for circulating cooling air alternately through said inner casingand through the passageway between said casings.

' I STUART OTTO.

LAWRENCE BRUEHL.

